As cardiovascular failure begins, the person may expertise difficulty deep breathing upon effort. As it worsens, he may turn into unable to catch his air even sleeping. This is often more noticeable during the night, requiring the pup to sleep straight in a lounge chair or along with his head enhanced on multiple pillows. A great audible wheeze may be present and he may well feel as he cannot take a full, deep breath. This may trigger him to be able to breathe swiftly. He may sense anxious and become unable to sleep well due to breathing difficulties.